thickness, length and shape of the specimen thus obtained would be much less than the above 

 mentioned standard size, the comparative ductility of "Steelcrete" mesh cannot be satisfactorily 

 shown by the method of "percentage of elongation." 



Any method of correcting the percentage of elongation of a specimen of "Steelcrete" mesh 

 for the difference in section, shape and length would only be roughly approximate. Moreover, it 

 would not be convincing, as it would require that the percentage of elongation actually obtained 

 be greatly increased in order to make the comparison of any value whatever. The average per- 

 centage of elongation of the specimens tested by Prof. Macgregor of the Columbia University 

 Testing Laboratory in New York City and elsewhere described, exceeds the requirements of the 

 Manufacturers Standard Specification (1914) and of the American Society of Testing Materials 

 (1913) for cold twisted square bars used in concrete reinforcement. This figure should be great- 

 ly increased in order to make the correction for the size and shape of the specimen. The percen- 

 tage of reduction of area offers a more satisfactory method of comparison. The percentage of 

 reduction of area of the test specimen? of "Steelcrete" mesh investigated by Mr. Macgregor av- 

 eraged forty per cent., indicating a high degree of ductility. 



171 



